Factors that influence reproductive success may act through their influence on dispersal and selection for audible territory. The social environment of mammals such as stress from interactions with same-sex conspecifics or stimulation by members of the opposite sex may affect the probability of success in there endeavors but the mechanisms involved are not well understood. Furthermore, the social environment may affect males and females in the same or in different ways. The aim of this study is to examine alternative hypotheses about whether or not there is a gender difference in the cues that influence emigration and immigration. The intra sexual competition hypothesis predicts that same-sexconspecifics will induce emigration but prevent immigration. In contrast, the inbreeding avoidance hypothesis predicts that opposite- sex conspecifics should induce emigration. The mate access hypothesis may work in conjunction with either of the two previous hypotheses and predicts that individuals will emigrate if there are no potential mates in the social group. Finally, the conspecific cuing hypothesis predicts that individuals will immigrate into territories containing same-sex conspecifics because their presence indicates that the territory is suitable. To test these hypotheses, I will examine preferences of young and mature female and male pine voles to different of olfactory and social cues in series of laboratory experiments. Lab experiments also will be conducted to examine responses of female and male residents to visitors of different sexes and age classes. Finally, I propose to examine the effects of group composition on intergroup transfer in lab and field experiments. I will test whether reproductive vacancies affect movement and whether the gender of remaining group members influences the timing and gender of immigrants. The long-term objectives of this research are to understand the factors involved in social control of behavior as well as to begin to understand the physiological mechanisms underlying these. Studies like the ones proposed here would allow me to examine the relationship between social interactions and dispersal, which ultimately affects the probability of reproduction. Interactions with conspecifics can also be important in the expression of gender-related behavior; this study will provide a model to access reproductive strategies in males and females.